This invention relates to a system for reducing the wing root bending load on an aircraft and more particularly, but not by way of limitation, to reducing the wing root bending load automatically when a threshold load level is exceeded during high speed maneuvers or other critical maneuvers.
Airplane wing structures are usually either maneuver-load or gust-load critical depending on whether the aircraft is a high performance-high maneuver aircraft or a transport type of aircraft. Although design objectives differ for these two different types of aircraft, the underlying principle of redistribution of airload to reduce wing structural loads and structural weights is the same. While the system described herein is for a maneuver critical wing, the same principle and control systems are applicable for a gust-critical wing.
Heretofore, various existing aircraft have wing-load-alleviation systems. Typical of these systems are those used with 747 and L-1011 aircraft and that are designed primarily for gust-alleviation with the benefits of improved ride comfort and extended structural fatigue life. The systems on these aircraft operate full time with commands to the wing surfaces being generated at all levels of disturbance. However, the system described in this application is unique in that it has a threshold level for commanding wing surfaces and is also potentially capable of commanding different wing surfaces on the aircraft based on the authority required to achieve the necessary level of load alleviation.
In the following United States Patents: U.S. Pat. Nos. 2,448,712 to Hampshire, 2,816,724 to Snodgrass, 3,790,106 to Sweeney et al, 3,814,912 to Manke et al, 3,940,094 to Kress et al, 4,027,839 to Quinlivan, 4,382,282 to Graham et al, various types of wing sweep control systems, high angle of attack systems, wing flap and trim control systems are shown. None of these prior art patents provide the unique features and advantages of the subject manuever load alleviation system.